20] 
KARRER AND WEBB—TITRATION CURVES OF CULTURE MEDIA 305 
The writers take pleasure in extending thanks to Dr. B. M. 
Duggar for many suggestions and criticisms; and to Dr. George T. 
Moore for the privileges and facilities of the Missouri Botanical 
arden. 
Graduate Laboratory, Missouri Botanical Garden. 
LITERATURE 
Clark, W. M., and Lubs, H. A. (17). The colorimetric determination of hydrogen 
ion concentration and its applications in bacteriology. I. Jour. Bact. 2: 
-84. f. 1-4. 1917. 
Duggar, B. M. (19). The micro-colorimeter in the indicator method of hydrogen 
ion determination. Ann. Mo. Bot. Gard. 6: 179-181. 1919 
Duggar, B. M., Severy, J. W., and Schmitz, H. (17). Studies in the physiology 
of the fungi. IV. The growth of certain fungi in plant decoctions. Ibid. 
4: 165-173. f.1-4. 1917. 
ag Ae Abg md election organische Nährstoffe. Jahrb. f. wiss. Bot. 28: 
E = a pm Die Beeinflussung des Wachstmus einiger Pilze durch 
chemische Reize. Ibid. 30: 665-688. 1897. 
Sörensen, S. P. L. (09). Enzymstudien II. Ueber die Messung und die Bedeutung 
der Wasserstoffionenkonzentration bei enzymatischen Prozessen. Biochem. 
Zeitschr. 21: 129-304. 1909. 
Zeller, S. M. , Schmitz, H., and Duggar, B. M. (19). Studies in the physiology 
inu. VI. Growth of wood-destroying fungi in liquid media. Ann. 
Mo. Bot. Gard. 6: 137-142. 1919. 
